Wave-signal antenna



Dec. 2, 1947. H. A. WHEELER 2,432,057

WAVE- S IGNAL ANTENNA Filed June 23. 1944 Resistance Reactunce .:T-j mayRg Lg l vsHEELE BY H68 fl nny fdr.

A ORNEY 'i aterited cc. 2, i947 WAVE-SIGNAL ANTENNA Harold A. Wheeler,Great Neck, N. Y., assignor, by mesne assignments, to HazeltineResearch, Inc., Chicago, 111., a corporation of Illinois ApplicationJune 23, 1944, Serial No. 541,747

12 Claims. 1

The present invention relates to wave-signal antennas and. particularly,to such antennas either of the shunt-fed or series-fed quarter-wavetype.

Wave-signal antennas having an effective electrical length of an oddnumber of quarter-wave lengths, usually one quarter-wave length, areconventionally coupled to a wave-signal translating apparatus through afeed transmission line which itself is coupled to the antenna by eithera so-called series-feed or shunt-feed arrangement.

In the series-feed type of coupling, the antenna is usually supportedwith its base mounted on an insulator and thus in spaced relation to aconductive ground surface. The transmission line is connected directlyor through a suitable impedance-matching transmission-line sectionacross the insulator. The use of a base insulator has the disadvantagesthat the insulator is subject to electrical and mechanical failure andintroduces substantial difllculties regarding the mechanical support ofthe antenna.

A shunt-fed antenna has its base mechanically and electrically connectedto the conductive ground surface, thereby avoiding the requirement ofbase insulators. One conductor of the transmission line is connected tothe conductive ground surface at the base of the antenna, while theother conductor extends at an angle to the conductive surface and isconnected to a point on the antenna usually located about one-fifth ofthe antenna height. The angle which the lastmentioned conductor makeswith the grounded surface is usually about 45 degrees, although thisangle and the height of the connection of the conductor to the antennamust usually be determined by trial. The inclined conductor forms withthe lower portion of the antenna, below the point of its connectiontherewith and with the ground return path provided by the conductivesurface, a closed conductive loop which matches the impedance of theantenna to the characteristic impedance of the transmission line. Thereis the disadvantage with this arrangement, however, that the feedtransmission line must terminate at a substantial distance from the baseof the antenna and the inclined conductor must then extend from there toa point on the antenna located a substantial distance from its groundedend. Frequently insufficient space is available around the base of theantenna for this purpose and an alternative form of antenna feed must beused generally at the expense of increasing the over-all antenna height,as in the J type of antenna where the antenna conductor has a Jconfiguration grounded at its base, or by the provision of a well sunkbelow the ground surface to accommodate a quarter-wave length portion ofthe base of the antenna.

There is the additional disadvantage, with any of the antenna systemsdescribed, that while the antenna impedance can be matched to thecharacteristic impedance of the feed transmission line at a givenfrequency, it is difl'icult to provide any form of compensating network,of the type disclosed in United States Letters Patent No. 2,064 7'74,granted December 15, 1936, to Harold,

A. Wheeler for Wave signal collecting system" r and assigned to the sameassignee as the present application, which enables the antenna topresent to the feed transmission line substantially constant impedanceover a predetermined range of operating frequencies.

It is an object of the present invention, therefore, to provide a newand improved wave-signal antenna which avoids one or more of thedisadvantages and limitations of prior antennas of the type described.

It is a further object of the invention to provide, in a system fortranslating wave signals within a predetermined range of wave lengths, anew and improved antenna which is adapted to have substantially uniformimpedance over such wave-length range and one in which uniformity ofimpedance is easily and readily effected by an antenna supportingstructure involving a relatively simple, sturdy and inexpensiveconstruction.

It is an additional object of the invention to provide a quarter-waveantenna of the shuntfed type which requires a minimum amount of mountingspace and which permits termination of a feed transmission lineimmediately adjacent the base of the antenna.

It is a further object of the invention to provide a new and improvedunitary antenna structure which does not require any electricalinsulation in its construction, one which may be directly supported fromand in electrical engagement with a conductive ground surface, and yetone which may be either of the series-fed or shunt-fed type, as desired,with transmissionline termination directly at the base of the an tenna.

In accordance with the invention there is provided, in a system fortranslating wave signals within a predetermined range of wave lengths,an antenna comprising an antenna. conductor adapted to be so mounted asto extend in a di-- rection away from a conductive surface with one endthereof spaced from the surface by a distance much less than onequarter-wave length at a predetermined wave length of the aforesaidrange and adapted to be coupled to a wave-signal translating apparatusby a lead-in conductor which extends from the surface in insulatedrelation therewith. The antenna includes a support conductor extendinglaterally from the aforesaid one end of the antenna conductor and havinga length substantially greater than the aforesaid distance formechanically and electrically connecting the said one end of the antennaconductor to the surface to support the antenna conductor thereon. Thelength of the antenna conductor is such as to provide by resonance atthe aforesaid predetermined wave length approximately maximum currenttherein at the said one end and the cross-sectional dimension of theportion of the support conductor between the surface and the said oneend of the antenna conductor is small enough to provide at leastone-tenth of the total inductance of the antenna conductor and the saidportion of the support conductor.

For a better understanding of the present invention. together with otherand further objects thereof. reference is had to the followingdescription taken in connection with the accompanying drawing. and itsscope will be pointed out in the appended claims.

Referring now to the drawing, Fig. 1 illustrates a wave-signal antennaembodying the present invention in a particular form; Fig. 2 representsthe equivalent circuit diagram of the Fig. 1 antenna arrangement andFigs. 3 and 4 represent simplified forms of equivalent circuit diagramsthereof, these circuit diagrams being used as an aid in explaining theoperation of the invention: Fig. 5 represents typical impedancecharacteristic of an antenna embodying the invention: and Figs. 6, 7 and8 illustrate several antenna arrangements embodying the presentinvention in individual modified forms.

Referring more particularly to Fig. 1 of the drawing. there isillustrated a wave-signal antenna of the quarter-wave series-fed typeembodying the present invention in a particular form. The antennacomprises an antenna conductor in having an effective electrical lengthof an odd number of quarter-wave lengths at a predetermined wave lengthin the range over which the antenna is to operate. The antenna conductorl preferably is a quarter-wave length long and is adapted to be mountedin extending relation from a conductive surface H. which for example maybe the surface of the ground or a conductive surface of a motor vehicleor naval vessel, with one end I: of the antenna spaced from the surfaceII by a distance much less than one quarter-wave length at the aforesaidpredetermined wave length. The antenna conductor II is adapted to becoupled to a wave-signal translating apparatus, not shown, by a coaxialtransmission line I 3 having a, predetermined characteristic impedanceZ0 and having the inner conductor thereof extending from the surface Iiin insulated relation therewith.

The antenna includes an elongated support conductor l4 positioned on theantenna side of the surface Ii in laterally or radially extendingrelation with the end l2 of the antenna conductor and approximatelyparallel with the conductive surface. The support conductor H has aneffective electrical length of approximately an. odd number of half-wavelengths, preferably a single half-wave length, and thus onesubstantially greater than the distance by which the end I2 of theantenna conductor is spaced from the conductive surface ii. It is thepurpose of the support conductor mechanically and electrically toconnect the end ii. of .the antenna conductor to the conductive surface,to support the antenna conductor l0 thereon, while at the same timepresenting to this end of the antenna conductor an impedance to groundas high as though a support of insulating material were used. Theconductor I 4 preferably has an approximate U-shaped configuration andis electrically and mechanically connected to the conductive surface i iat its ends, as by machine screws l5, it, with the center of the supportconductor spaced from the surface I i and supporting normal thereto andin electrical engagement therewith the antenna conductor iii. The lengthof the antenna conductor in is such as to provide by resonance at thepredetermined wave length aforementioned approximately maximum currenttherein at its end l2. The crosssectlonal dimension of the portions ofthe support conductor I4 between the surface I! and the end i2 of theantenna conductor is sufllciently small as to provide at least one-tenthof the sum of the inductance of the antenna conductor and the parallelinductance of these portions of the support conductor.

As will be pointed out in greater detail hereinafter, the proportioningof the antenna conductor I0 and the support conductor id in the mannerdescribed causes the antenna conductor to have a predominantlycapacitive reactance and the support conductor I a predominantlyinductive reactance. There is provided a condenser connected in serieswith the transmission line l3 and having a value so related to thepredominant capacitive reactance of the antenna l0 and the predominantinductive reactance of the support id as to provide by resonance anantenna impedance at the end l2 of the antenna conductor which issubstantially constant over the range of operating wave lengths of theantenna. This condenser is provided by a conductive member l'i which isconnected to the inner conductor l8 of the transmission line i3 and issecured in a central bore 19 of an insulator 20. The latter has'aconical end portion 2| over which is secured a conductive cap member 22.The latter is electrically connected to the end l2 of the antennaconductor i0 and to the support conductor I4 at its center by aconductive flexible strap member 23. The insulator 20 is secured in asmall well 24. provided in the conductive surface II, by a ring member25 which extends over a flanged base portion 26 of the insulator. Theouter conductor of the transmission line i3 is electrically andmechanically secured to the edge of an aperture 21 provided centrally ofthe floor of the well 24. A suitable drain, not shown. may be providedin the well 24 by which to permit accumulated moisture to drain out ofthe well.

Considering now the operation of the antenna just described, Fig. 2represents schematically the equivalent circuit diagram of the antennawith the distributed inductance and capacitance of the antenna conductorin represented as lumped inductors L10 and C10, respectively, and theradiation resistance of the antenna conductor represented by a resistorR10. In similar manner, the distributed inductance and capacitance ofthe arms of the support conductor H are represented as equal lumpedinductors L14, L14 and lumped parallel-connected condensers C14, C14.

The outer conductor of the transmission line terminates and is groundedat the bottom of the well 24, whereas the inner conductor l8 of thetransmission line extends on to the conductive member I1 positionedwithin and near the top of the insulator 20. As is well known, theunshielded portion of the transmission-line conductor I8 has distributedinductance which, with the distributed inductance of the conductivemember I! and the strap member 23, is represented in Fig. 2 by thelumped inductor Lia. The condenser, comprised by the member I! and thecap 22 associated with the insulator 20, is represented in Fig. 2 by thecondenser CPI-22. The end of the antenna conductor I0 is indicated inFig. 2 as the junction point between the inductors L14, L14 and L10.

It will be a parent that the inductors L14, L14 are connected betweenthe point l2 and ground so that they may be represented by a singlelumped indicator 1/14 as in Fig. 3, having a value of inductanceone-half that of either of the inductors L14, L14. Similarly, thecondensers C14, C14 are connected in parallel between the point I2 andground so that they may be replaced by a single condenser 0'14. asrepresented in Fig. 3, having a value twice that of either of thecondensers C14, C14. The schematic circuit of Fig. 3 may thus beconsidered a somewhat simplified form of equivalent circuit diagram ofthe Fig. 1 antenna. Additionally there is included in the Fig. 3 circuitdiagram. a resistor R1: which represents the characteristic impedance Z0of the coaxial transmission line l3.

It will be apparent from Fig. 3 that the antenna essentially comprisestwo series-resonant circuits coupled by a shunt-resonant third circuit.The constants of these resonant circuits are proportioned in accordancewith the teachings of the aforesaid Wheeler patent to provide a value ofantenna impedance equal to the characteristic impedance Z0 of thetransmission line l3 and one which remains substantially constant overthe range of operating wave lengths of the antenna. This isaccomplished. of course, by adjustment of the length of the antennaconductor ID, by adjustment of the length and cross-sectionalconfigurations of the support conductor M, by the selection of thelength of the inner conductor l8 of the transmission line l3 whichextends beyond the outer conductor thereof, and by the selection of thesize and spacing of the condenser elements I! and 22. The method bywhich this proportioning may be carried out will be readily apparent toone skilled in the art.

As previously mentioned, the antenna conductor In is proportioned tohave a predominant capacitive reactance, while the support conductor I4is proportioned to have a predominant inductive reactance. Fig. 4represents an even more simplified equivalent circuit diagram of theantenna wherein only the predominant capacitive reactance of the antennaconductor 10 is represented as an equivalent condenser (3'10 and thepredominant inductive reactance of the support conductor is representedas an equivalent inductor Ln. The size and spacing of the conductive cap22 and conductive member I! associated with the insulator 20 are soselected that the condenser provided thereby has a capacitive reactanceslightly larger than the sum of the inductive reactances of the extendedportion of the inner conductor iii of the transmission line l3, themember l1, and the strap member 23. The net capacitance provided by theelements 11 and length corresponding to the mean frequency of thefrequency range over which the antenna is to operate.

Fig. 5 represents the impedance characteristic of an antenna when theelements thereof are proportioned in the manner last described. As thereindicated, the impedance of the antenna at any wave length A may have areactive and resistive component. The coaxial transmission line l3,which is connected to the antenna, has a characteristic impedance Z0which is resistive and is plotted on the axis of ordinates in Fig. 5.Curve A represents the impedance of the antenna as seen by the coaxialtransmission line. It will be seen from curve A that the antennaimpedance, over the range from a first wave length it to a second wavelength X2, is substantially equal to the characteristic impedance Z0 ofthe transmission line. This ensures maximum transfer of power betweenthe transmission line l3 and the antenna over the wave-length range 7mto M.

In certain applications, it may be necessary to shorten somewhat thelength of the support conductor H to minimize the mounting spacerequired by the antenna. Fig. 6 schematically illustrates an antennaembodying a modified form of the invention which permits this while, atthe same time, maintaining the antenna characteristics and its mode ofoperation substantially that described in connection with the Fig. 1antenna. In Fig. 6, elements corresponding to similar elements of Fig. 1are designated by similar reference numerals and analogous elements bysimilar reference numerals primed. While no attempt is made in Fig. 6for purposes of simplicity to show the detailed construction of theantenna aside from the main constructional features, it will beunderstood that the detailed construction may follow along lines similarto those of the Fig. 1 antenna. In the present embodiment, the supportconductor M is somewhat shortened physically. but its effectiveelectrical length is maintained at the desired value by the provision ofa capacitor member 28 which is electrically and mechanically secured tothe support I4 and extends laterally from the end l2 of the antennaconductor ID in approximately parallel spaced relation to the conductivesurface I l. The capacitor member 28 effectively comprises a lumpedcapacitance positioned at the center of the support conductor 14' andthus has the effect of increasing the effective electrical length of thelatter. Consequently, it will be apparent that the length of thecapacitor member 28 varies inversely with that of the support conductorl4 and has a value such that the effective electrical length of thesupport conductor 14' is the same I as though its physical length wereincreased to the desired value described above in connection with theFig. 1 antenna construction. The operation of this modified form of theinvention is otherwise essentially similar to that of the Fig. l antennaarrangement and will not be repeated.

Fig. 7 represents schematically an antenna embodying a modified form ofthe invention, which is essentially similar to the antenna of Figs. 1and 6 and similar elements are designated by similar reference numeralsand analogous elements by similar reference numerals double primed. Thepresent antenna, which also may have constructional details of the typeindicated in Fig. 1, involves a somewhat simplified construction in thatthe support conductor I 4" has an L-shaped configuration and ismechanically and electrically connected to the conductive surface llonly at one of its ends 29. The points along the support conductor H" atwhich the end 12 of the antenna conductor Ill and the inner conductor l8of the transmission line i3 are connected thereto depend upon theeffective electrical length of the antenna conductor l and thecharacteristic impedance of the transmission line 13. In greater detail,the support conductor M" has a physical length such that its efiectiveelectrical length is one quarter-wave length at a wave length in therange over which the antenna is to operate, preferably the mean wavelength of such range. The antenna conductor I0 is connected to thesupport [4" at a point such that the conductive path from the free endof the antenna conductor l0 through the support conductor l4" to theconductive surface II has an effective electrical length ofapproximately an odd number of quarter-wave lengths at the predeterminedwave length last mentioned. In practice, the length of this conductivepath preferably is one quarterwave length. At the same time, thecross-sectional dimensions of the support conductor 14" are soproportioned that the portion of the support conductor between theconductive surface II and the end I2 of the antenna conductor I0 issmall enough to provide at least one-tenth of the total inductance ofthe antenna conductor and this portion of the support conductor. Inparticular, the dimensions of this portion of the support conductor areselected to provide the desired uniformity of antenna impedanceover theband of operating wave lengths of the antenna. The inner conductor l8 ofthe transmission line 13 is coupled to a point alongthe length of thesupport conductor [4 such that the impedance between this point and theconductive surface ll properly terminates the transmission line i3 inits characteristic impedance Zn. The constants of the antenna areproportioned in the manner described in connection with the antenna ofFig. 1 so that it presents to the transmission line l3 a substantiallyconstant value of impedance over the range of operating wave lengths ofthe antenna. The operation of the antenna is otherwise similar to thatof the Fig. 1 antenna and will not be repeated.

An even more simplified form of antenna is schematically represented inthe modified form of the invention of Fig. 8 which is essentiallysimilar to the antenna constructions heretofore described, similarelements being designated by similar reference numerals and analogouselements by similar reference numerals triple primed. The presentantenna construction is quite similar to that of Fig. 7 except that theL-shaped support conductor M' is connected at one end to the conductivesurface H and is connected at its other end to the end l2 of the antennaconductor I0. In the present arrangement, the cross-sectional dimensionsof the support conductor 1', its length, and its spacing from theconductive surface II are so proportioned that the effective electricallength of the conductive path from the free end of the antenna conductorl0 over the support conductor 14" to the conductive surface ii is an oddnumber of quarterwave lengths, preferably one quarter-wave length, andat the same time the impedance of the support conductor W is such asproperly to terminate the transmission line 13 in its characteristicimpedance Zo.

From the above description of the invention, it will be apparent that anantenna embodying the invention has substantially uniform impedance overa predetermined range of operating wave lengths and is one in whichuniformity of its impedance is easily and readily effected by an antennaand a supporting structure therefor of relatively simple, sturdy andinexpensive construction. Additionally, an antenna embodying theinvention has the important advantages that it avoids the use of anyinsulating material in its construction, yet may be operated as ashuntfed or series-fed antenna..as desired. Further, the antenna.requires a :minimum amount of mounting space and permits the terminationof a transmission line at a point immediately adjacent the base of theantenna. when operated as a shunt-fed antenna, rather than at asubstantial distance to one side thereof as has heretofore been requiredin prior shunt-fed antennas.

While there have been described what are at present considered to be thepreferred embodiments of this invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the invention, and it is, therefore.aimed in the appended claims to cover all such changes and modificationsas fall within the true spirit and scope of the invention.

What is claimed is:

1. In a system for translating wave signals within a predetermined rangeof wave lengths, an antenna comprising, an antenna conductor adapted tobe so mounted as to extend in a di rection away from a conductivesurface with one end thereof spaced from said surface by a distance muchless than one quarter-wave length at a predetermined wave length in saidrange and adapted to be coupled to a wave-signal translating apparatusby a lead-in conductor which extends from said surface in insulatedrelation therewith, and a support conductor extending laterally fromsaid one end of said antenna conductor and having a length substantiallygreater than said distance for mechanically and e.ectricaliy connectingsaid one end of said antenna conductor to said surface to support saidantenna conductor thereon, the length of said antenna conductor beingsuch as to provide by resonance at said predetermined wave lengthapproximately maximum current therein at said one end and thecross-sectional dimensions of the portion of said support conductorbetween said surface and said one end of said antenna conductor beingsmall enough to provide at least one-tenth of the total inductance ofsaid antenna conductor and said portion of said support conductor. I

2. In a system for translating wave signals within a predetermined rangeof wave lengths, an antenna comprising, an antenna conductor adapted tobe so mounted as to extend in a direction away from a conductive surfacewith one end thereof spaced from said surface by a distance much lessthan one quarter-wave length at a predetermined wave length in saidrange and adapted to be coupled to a wave-signal translating apparatusby a lead-in conductor which extends from said surface in insulatedrelation therewith, and a support conductor positioned on the antennaside of said surface in laterally extending relation to said one-end ofsaid antenna conductor and having a length substantially greater thansaid distance for mechanically and electrically connecting saidone endof said antenna conductor to said surface to support said antennaconductor thereon, the length of said antenna conductor being such as toprovide by resonance at said predetermined wave length approximatelymaximum current therein at said one end and the cross-sectionaldimensions of the portion of said support conductor between said surfaceand said one end of said antenna conductor being small enough to provideat least onetenth of the total inductance of said antenna. conductor andsaid portion of said support conductor.

3. In a system for translating wave signals within a predetermined rangeof wave lengths, an antenna comprising, an antenna conductor adapted tobe so mounted as to extend in a direction away from a conductive surfacewith one end thereof spaced from said surface by a distance much lessthan one quarter-wave length at a predetermined wave length in saidrange and adapted to be coupled to a wave-signal translating apparatusby a lead-in conductor which extends from said surface in insulatedrelation' therewith, and a support conductor extending laterally fromsaid one end of said antenna conductor and having a length substantiallygreater than said distance for mechanically and electrically connectingsaid one end of said antenna conductor to said surface to support saidantenna conductor thereon, the conductive path from the other end ofsaid antenna conductor to said surface traced through said supportconductor having an effective electrical length of approximately an oddnumber of quarter-wave lengths at said predetermined wave length and thecross-sectional dimensions of the portion of said support conductorbetween said surface and said one end of said antenna conductor beingsmall enough to provide at least one-tenth of the total inductance ofsaid antenna conductor and said portion of said support conductor.

4. In a system for translating wave signals within a predetermined rangeof wave lengths, an antenna comprising, an antenna conductor adapted tobe so mounted as to extend in a direction away from a conductive surfacewith one end thereof spaced from said surface by a distance much lessthan one quarter-wave length at a predetermined wav length in said rangeand adapted to be coupled to a wave-signal translating apparatus by alead-in conductor which extends from said surface in insulated relationtherewith, and a support conductor extending radially from said one endof said antenna conductor approximately parallel to said surface andhaving a length substantially greater than said distance formechanically and electrically connecting said one end of said antennaconductor to said surface to support said antenna conductor thereon, thelength of said antenna conductor being such as to provide by resonanceat said predetermined wave length approximately maximum current thereinat said one end and the cross-sectional dimensions of the portion ofsaid support conductor between said surface and said one end of saidantenna conductor being small enough to provide at least one-tenth ofthe total inductance of said antenna conductor and said portion of saidsupport conductor.

5. In a system for translating wave signals within a predetermined rangeof wave lengths, an antenna comprising, an antenna conductor adapted tobe so mounted as to extend in a direction away from a conductive surfacewith end of said antenna conductor and having a length substantiallygreater than said distance for mechanically and electrically connectingsaid one end of said antenna conductor to said surface to support saidantenna conductor thereon, the length of said antenna conductor beingsuch as to provldeby resonance at said predetermined wave lengthapproximately maximum current therein at said one end and thecross-sectional dimensions of the portion of said support conductorbetween said surface and said one end of said antenna conductor beingsmall enough to provide at least one-tenth of the total inductance ofsaid antenna conductor and said portion of said support conductor.

6. In a system for translating wave signals within a predetermined rangeof wave lengths, an antenna comprising, an antenna conductor adapted tobe so mounted as to extend in a direction away from a conductive surfacewith one'end thereof spaced from said surface by a distance much lessthan one quarter-wave length at a predetermined wave length in saidrange and adapted to be coupled to a wave-signal translating apparatusby a lead-in conductor which extends from said surface in insulatedrelation therewith, and an approximately L-shaped support conductorextending laterally from said one end of said antenna conductor andhaving an over-all length equal substantially to an odd number ofquarter-wave lengths at said predetermined wave length for mechanicallyand electrically connecting said one end of said antenna conductor tosaid surface to support said antenna conductor thereon, the length ofsaid antenna conductor being such as to provide by resonance at saidpredetermined wave length approximately maximum current therein at saidone end and the cross-sectional dimensions of the portion of saidsupport conductor between said surface and said one end of said antennaconductor being small enough to provide at least one-tenth of the totalinductance of said antenna conductor and said portion of said supportconductor.

7. In a system for translating wave signals within a predetermined rangeof wave lengths, an antenna comprising, an antenna conductor adapted tobe so mounted as to extend in a direction away from a conductive surfacewith one end thereof spaced from said surface by a distance much lessthan one quarter-wave length at a predetermined wave length in saidrange and adapted to be coupled to a wave-signal translating apparatusby a lead-in conductor which extends from said surface in insulatedrelation therewith, and a support conductor extending in a plurality ofdirections laterally from said one end of said antenna conductor andhaving in each of said directions a length substantially greater thansaid distance for mechanically and electrically connecting said one endof said antenna conductor to said surface to support said antennaconductor thereon, the length of said antenna conductor being such as toprovide by resonance at said predetermined wave length approximatelymaximum current therein at said one end and the 15 cross-sectionaldimensions of the portions of said support conductor between saidsurface and said one' end of said antenna conductor being small enoughto provide at least-one-tenth of the sum of the inductance of saidantenna conductor and the inductance of said portions of said supportconductor in parallel.

8. In a system for translating wave signals within a predetermined rangeof wave lengths, an antenna comprising.-an antenna conductor adapted tobe so mounted as to extend in a direction away from a conductive surfacewith one end thereof spaced from said surface by a distance much lessthan one quarter-wave length at a predetermined wave length in saidrange and adapted to be coupled to a wave-signal translating apparatusby a lead-in conductor which extends irom said surface in insulatedrelation,

therewith, and an elongated support conductor mechanically andelectrically connected to said surface at each of its ends with thecenter thereof spaced from said surface by said distance and supportingnormal thereto and in electrical engagement therewith said antennaconductor, the length of said antenna conductor being such as to provideby resonance at said predetermined wave length approximately maximumcurrent therein at said one end and the cross-sectional dimensions ofthe portions of said support conductor between said surface and said oneend of said antenna conductor being small enou h to provide at leastone-tenth of the sum of the inductance of said antenna conductor and theinductance of said portions of said support conductor in parallel.

9. In a system for translating wave signals within a predetermined rangeof wave lengths, an antenna comprising, an antenna conductor adapted tobe so mounted as to extend in a direction away from a conductive surfacewith one end thereof spaced from said surface by a distance much lessthan one quarter-wave length at a predetermined wave length in saidrange and adapted to be coupled to a wave-signal translating apparatusby a lead-in conductor which extends from said surface in insulatedrelation therewith,

and an approximately U-shaped support conductor extending symmetricallyin lateral directions from said one end of said antenna conductor andhaving an effective electrical length equal approximately to an evennumber of half-wave lengths at said predetermined wave length formechanically and electrically connecting said one end of said antennaconductor to said surface to support said antenna conductor thereon, thelength of said antennav conductor being such as to provide by resonanceat said predetermined wave length approximately maximum current thereinat said one end and the cross-sectional dimensions of the portions ofsaid support conductor between said surface and said one end of saidantenna conductor being small enough to provide at least one-tenth ofthe sum of the inductance of said antenna conductor and the inductanceof said portions of said support conductor in parallel.

10. In a system for translating wave signals within a predeterminedrange of wave lengths, an antenna comprising, an antenna conductorhaving an effective electrical length of an odd num ber of quarter-wavelengths at a predetermined wave length in said range and adapted tobe somounted as to extend in a direction away from a conductive surface withone end thereof spaced from said surface by a distance much less thanone quarter-wave length at said predetermined wave length and adapted tobe coupled to a wave-signal translating apparatus by a lead-in conductorwhich extends from said surface in insulated relation therewith, and anelongated support conductor having an effective electrical length of aneven number of half-wave lengths at said predetermined wave length andbeing mechanically and electrically connected to said surface at each ofits ends with the center thereof spaced from said surface by saiddistance and supporting normal thereto and in electrical engagementtherewith said antenna conductor, the cross-sectional dimensions of theportions of said support conductor between said surface and said one endof said antenna conductor being small enough to provide at leastone-tenth of the sum of the inductance of said antenna conductor and theinductance of said portions of said support conductor in parallel.

11. In a system for translating wave signals within a predeterminedrange of wave lengths, an antenna comprising, an antenna conductoradapted to be so mounted as to extend in a direction away from aconductive surface with one end thereof spaced from said surface by adistance much less than one quarter-wave length at a predetermined wavelength in said range and adapted to be coupled to a wave-signaltranslating apparatus by a transmission line having a predeterminedcharacteristic impedance and having a conductor thereof extendingfromsaid surface'in insulated relation therewith, a support conductorextending laterally from said one end of said antenna conductor andhaving a length substantially greater than said distance formechanically and electrically connecting said one end of said antennaconductor to said surface to support said antenna conductor thereon, thelength of said antenna conductor being such as to provide by resonanceat said predetermined wave length approximately maximum current thereinat said one end and the cross-sectional dimensions of the portion ofsaid support conductor between said surface and said one end of saidantenna conductor being small enough to provide at least one-tenth ofthe total inductance of said antenna conductor and said portion of saidsupport conductor, and means for connecting said conductor of saidtransmission line to a point on said support conductor having a value ofimpedance equal to said characteristic impedance.

12. In a system for translating wave signals within a predeterminedrange of wave lengths, an antenna comprising, an antenna conductoradapted to be so mounted as to extend in a direction away from aconductive surface with one end thereof spaced from said surface by adistance much less than one quarter-wave length at a predetermined wavelength in said range and adapted to be coupled to a wave-signaltranslating apparatus by a lead-in conductor which extends from saidsurface in insulated relation therewith, a support conductor extendinglaterally from said one end of said antenna conductor and having alength substantially greater than said distance for mechanically andelectrically connecting said one end of said antenna conductor to saidsurface to support said antenna conductor thereon, the length of saidantenna conductor being such as to provide by resonance at saidpredetermined wave length approximately maximum current therein at saidone end and the cross-sectional dimensions of the portion of saidsupport conductor between said surface and said one end of said antennaconductor being small 14 conductor and having a value so related to saidcapacitive and inductive reactances as to provide by resonance anantenna impedance at said one end which is substantially constant oversaid pre- 5 determined range of wave lengths.

HAROLD A. WHEELER.

